Process for making tetraethyl lead



Patented Oct. 27, 1953 PROCESS FOR MAKING TETRAETHYL Nelson Whitman, Wilmington, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application February 14, 1952, Serial No. 271,630

4 Claims. 1

This invention relates to a process for the manufacture of tetraethyl lead and more particularly to a process for improving the yields of tetraethyl lead.

Tetraethyl lead is a valuable compound which has been manufactured on a large scale for many years. The demand for it is continually increasing and hence the production has increased accordingly and now amounts to millions of pounds a month. Accordingly, even slight improvements in yield, amounting to only a fraction of a per cent, are important commercially and economically.

Tetraethyl lead is made by reacting ethyl chloride with lead monosodium alloy (NaPb). For many years, the process was carried out at temperatures of from about 65 C. to about 85 C. with yields of tetraethyl lead of about 75% to about 85%, such process ordinarily requiring reaction periods of or more hours for completion. George E. Holbrook, in Patent No. 2,464,397, has disclosed that such reaction can be accelerated and the yield of tetraethyl lead increased to the range of about 85% to about 90% by carrying out such reaction in the presence of from about 0.005% to about 4% by weight based on the ethyl chloride of a ketone, preferably acetone. By the use of such ketones, particularly acetone, the reaction period is reduced to less than 2 hours, usually about 90 minutes. For some years, the

commercial manufacture of tetraethyl lead has been carried out in the presence of acetone in accordance with the teachings of Holbrook.

It is an object of the present invention to provide an improved process for manufacturing tetraethyl lead. A further object is to provide a method for increasing the yields of tetraethyl lead over those obtained by the processes heretofore employed. Other objects are to advance the art. Still other objects will appear hereinafter.

The above and other objects may be accomplished in accordance with my invention which comprises carrying out the reaction ofethyl chloride on lead monosodium alloy in the presence of from about 0.005% to about 4% by weight of acetone and of from about 0.005% to about 0.06% by weight of acetylene, both based on the weight of ethyl chloride present. By such process, the yield of tetraethyl lead is significantly increased.

It has been found that, when it is attempted to react ethyl chloride with lead monosodium alloy in the presence of acetylene and in the absence of acetone and like accelerating agents, the yield of tetraethyl lead is appreciably decreased.

However, I have found that, when such reaction is carried out in the presence of both acetone and acetylene, the yields are increased. Such latter result was entirely unexpected and contrary to that which could be predicted.

The amount of acetone employed may vary from about 0.005% to about 4% by weight based on the ethyl chloride and, preferably, from about 0.1% to about 0.4% by weight.

The acetylene may vary from about 0.005% to about 0.06% by weight based on the ethyl chloride and, preferably, from about 0.01% to about 0.03% by weight.

The acetone and the acetylene may be added in any desired manner, but, ordinarily, will be dissolved in the ethyl chloride before the ethyl chloride is brought into contact with the alloy.

My process may be carried out in the equipment and under the conditions of temperature and pressure which have been heretofore employed in the manufacture of tetraethyl lead and which are well known to the art. Preferably, the process will be carried out at temperatures of from about C. to about C. and corresponding pressures of from about 107 to about 255 pounds per square inch absolute, employing ethyl chloride in excess of the amount theoretically required for the reaction and up to about 4 times the weight of the alloy. The alloy corresponds closely to the composition NaPb, ordinarily containing between 9.9 and 10.1% of sodium by weight and, preferably, exactly 10% by weight of sodium. The process may be carried out in batches or continuously, the higher temperatures and pressures and the higher proportions of ethyl chloride usually being employed in the continuous process.

In order to more clearly illustrate my invention, preferred modes of carrying the same into effect and the advantageous results to be obtained thereby, the following example is given:

EXAIWPLE lene required were added as gaseous acetylene.

contained in glass flasks with ground closures,

except that, when 0.029% or more of acetylene was added, it was dissolved directly in the ethyl chloride. Each bomb was stored on ice until all the bombs had been loaded.

The loaded bombs were placed in a tumbling machine as rapidly as possible. As each bomb was removed from the ice bath, it was given a sharp blow with a hammer to break the alloy and acetylene bulbs within the bomb. The bombs in the tumbling machine were covered with water which was raised in temperature fromroom temperature to 85 C. in about 9 minutes, at which temperature the bombs were tumbled for 90 minutes. After the heating period, the hot water was replaced with cold water and the bombs were.

Acetone, Acetylene, Wlt. peircent Wtt. pgrcent glggfg ase on ase on Etc] Etcl Increase 0. 09 0. 006 0. 86 0. 09 0. 012 l. 0. 09 0. 017 0. 80 0. 09 0. 029 0. 31 0. l3 0. 029 0. 85 0. 26 0. 012 0. 80 0. 26 0. 029 0. 56 0. 26 0. 035 0. 43 O. 26 O. 058 0. 69 0. 39 0. 017 0. 76 0. 39 0. 058 0. 89 0. 0 0. 017 -5 0. 0 0. 029 34 The last two experiments of the series are given for comparative purposes and show that acetylene alone, in the absence of acetone, seriously decreases the yields of tetraethyl lead.

It will be understood that the preceding example is given for illustrative purposes solely and that my invention is not limited to the specific embodiments disclosed therein. 0n the other hand, variations can be made in the proportions, conditions and equipment employed within the scope of the general description without departing from the spirit or scope of my invention.

From the preceding description, it will be apparent that, by my invention, I have provided a novel and improved process for making tetraethyl lead, whereby the yields of tetraethyl lead are significantly increased. While such increase in yields do not, on their face, appear to be particularly large, they represent an important economical advantage, particularl in view of the large scale upon which tetraethyl lead is manufactured. Accordingly, I believe that my invention constitutes a valuable contribution to and advance in the art.

I claim:

1. In the process for making tetraethyl lead by the reaction of ethyl chloride on lead monosodium alloy, the improvement which comprises carryingout such reaction in the presence of from about 0.1% to about 0.4% by weight of acetone and of from about 0.005% to about 0.06% by weight of acetylene, both based on the weight of ethyl chloride present.

2. In the process for making tetraethyl lead by the reaction of ethyl chloride on lead monosodium alloy, the improvement which comprises carrying out such reaction in the presence of from about 0.1% to about 0.4% b weight of acetone and of from about 0.01% to about 0.03% by weight of acetylene, both based on the weight of ethyl chloride present.

3. In the process for making tetraethyl lead by the reaction of ethyl chloride on lead monosodium alloy, the improvement which comprises carrying out such reaction at a temperature of from about C. to about C., a corresponding pressure of from about 107 to about 255 pounds per square inch absolute, and in the presence of from about 0.1% to about 0.4% by weight of acetone and of from about 0.005% to about 0.06% by weight of acetylene, both based on the weight of ethyl chloride present.

4. In the process for making tetraethyl lead by the reaction of ethyl chloride on lead monosodium alloy, the improvement which comprises carrying out such reaction at a temperature of from about 80 C. to about 120 C., a corresponding pressure of from about 107 to about 255 pounds per square inch absolute, and in the presence of from about 0.1% to about 0.4% b weight of acetone and of from about 0.01% to about 0.03% by weight of acetylene, both based on the weight of ethyl chloride present.

NELSON WHITMAN.

References Cited in thefile of this patent UNITED STATES PATENTS Number Name Date 2,464,397 Holbrook Mar. 15, 1949 

1. IN THE PROCESS FOR MAKING TETRAETHYL LEAD BY THE REACTION OF ETHYL CHLORIDE ON LEAD MONOSODIUM ALLOY, THE IMPROVEMENT WHICH COMPRISES CARRYING OUT SUCH REACTION IN THE PRESENCE OF FROM ABOUT 0.1% TO ABOUT 0.4% BY WEIGHT OF ACETONE AND OF FROM ABOUT 0.005% TO ABOUT 0.06% BY WEIGHT OF ACETYLENE, BOTH BASED ON THE WEIGHT OF ETHYL CHLORIDE PRESENT. 